Process of treating metatitanic acid



Patented Dec. 16, 1952 TED STATES PATENT OFFICE PROCESSOF TREATING META'TITANIO'ACID Max J. Mayer, Scarsdale,-N. Y.

No Drawing. Original applicationiOctober 24, .1946, SerialNo. 705,494, "Dividedand' tliisap- *plication October 18, 1950;"SerialNoL"l90I889 6 Claims.

win solutions vary in concentration of T102,

amount of trivalent titanium is formed. A seeding agent in the form of metatitanic acid or dispersedmetatitanic acid sol is then added, after which the solution isheated to the boiling point to fiecthydrolysis. The resulting precipitate consists of metatitanic acid which contains varying amounts of sulfuric acid, i. e. between 8% and 12% calculated on the basis of TiOz. The sulfuric'acidis not absorbedby the'TiOz but forms part of t-he crystal lattice. Recoveries of metatitanic acid hydrolysate amount to 90-98% of the TiOz in the solution. After filtration, the hydrolysate is washed-with dilute sulfuric acid until the iron content of the metatitanic acidis '.less =than0.01%. "Theiiltered metatitanic acid tpulp'then consists of about Percent TiOz 35 *H2SO4 3.5 "Water 61.5

.-.'I-he sulfuric acid content 'ofthe precipitate can -;be removed' by calcination at high temperatures.

-For1nearly complete removal of the S03, a temperature' above 800". C; is required. The following -.tablesshowsthe-effect of heat treatment upon the .removalofssulfuric acid from: the :TiOz. T102 so atreatedahadroriginally-9i37% H2SO4 on the basis .of sTiOzcontent. :The material washeatd to "M350 0. which was ;-maintained for. one hour. A.

tent. "The' "calcination'"temperature was then raised: to'4'50 C. and ='maintained for one hour, after which another sample was taken for analysis of "the HzSOrcontent. *The heatingwas'con- -tinued in'li-ke manner at the stages'of 550 0., 600 Crand 750 C.,"the'temperaturemaintained "for one hour *at each-of these stages, with a sample"being' taken at the end' of each stagefor determinatiomofthe H28 04 content.

I-IzSOr, ferrous sulfate and other minor metallic TABLE "impurities-that are in the form of sulfates, such as magnesium sulfate, aluminum sulfate, etc. Temperature fifig typical'solution; is of the following compo- Simon 1 5 Percent Grams per liter Re'duced 'IiO2 2 I g-gg Fe 0:92

Total H2804 550 20 Active Hzso 445 During calcination, the metatitanic acid under- Inorderto have an of the iron Sulfate in goes considerableshrinkage and is. converted to *valent form,- the solutions are reduced with iron, m f Tloz'of-anatfase chemlcal z'inc,'or other suitable material, until a small 5 reactlvlity-of such Tloz'ls-very-shghtsulfunc .acid andalkaline solutions showvery little or no reaction thereto.

Abetter procedure thancalcinationfor removal of the H2804 in the precipitated metatitanic acid :purified byfwa shing ,as heretofore described consists injurther. treatment with. alkali. After complete"neutralization, .the .resulting r-sulfate solution is removedby :washing, preferably. with condensed or deionized .Water. The washingat the outset. causes no difficulty butsaftermost of the sulfate solution. is removed, the. precipitate rbegins to .peptize, i. e.,- becomes colloidal. The filtration is then very. difiicult; and. handling of large quantities becomes well-nigh impossible. The change of particle size incident to colloidiza- 40 tion of. the-precipitate. is highly-undesirable for -many purposes.

...Among the. objectsof this invention is toxprovide a .process whereby. theiforegoing peptization -or colloidization is .avoided,..sov that, thewashing .andfiltration may be carried outefiiciently. and

rapidly.

A still further object .of this invention isto avoid the foregoing peptization. by inexpensive means and Without impairing the value of. the

purifiedmetatitanic acid for use in production of high quality titanium dioxide pigment.

'Other, further, and "more specific objects of this inventionwill become readily apparent to persons skilled in the art from a consideration .of

ftestssample was taken'zianditestediforH2804 con- '55 -thefollowing description,

According to the present invention, the metatitanic acid is slurried with water and to the slurry is added a solution of salts of elements which form with the hydroxides and carbonates of ammonium and of the alkali metals waterinsoluble, white hydroxides, carbonates, or basic carbonates, that calcine to white oxides. In lieu of the water-soluble salts, the corresponding oxides, hydroxides, carbonates or basic carbonates of these elements may be employed. These will react with some of the S04 content of the metatitanic acid to form soluble sulfates of these'elements.

Compounds of the elements of groups 2 to 5 of the periodic table, viz, those forming the aforementioned white, insoluble oxides, hydroxides, carbonates or basic carbonates, can be used according to this invention. The preferred compounds are those of Be, Cd, Al, La, Zr, Ce, Th, Cb, Sb and Ta, either alone or in combination. Compounds of elements which form insoluble sulfates, such as the Ca, Ba, Sr and Pb compounds,

are not suitable. Compounds of Mg and Zn are operative when alkali metal compounds are used for neutralization, but are not operative when ammonium compounds are used for neutralization, because, surprisingly, I have found that any small amount of ammonium sulfate thus formed promotes solubility of the hydroxides of 7 Mg and Zn.

Neutralization of the H2804 in the metatitanic acid, and precipitation of the white, insoluble hydroxides, carbonates, or basic carbonates, are

. then effected with aqueous solutions of the abovementioned alkaline materials. Since a surplus of the alkaline reagents is not obiectionable, pH values greater than '7 may be employed. jI prefer to use pH values of '7 to 12.

' soluble oxides, hydroxides, carbonates, or basic carbonates to the neutralized metatitanic acid. with thorough stirring.

In all of the above cases, owing to the presence of the insoluble oxides. hydroxides, carbonates, or basic carbonates in the metatitanic acid, substantially all of the sulfates can be washed out without any peptization or colloidization of the precipitate.

The minimum amount of insoluble oxides, hydroxides, carbonates, or basic carbonates, calculated as metal oxides and based on the TiOz content of the metatitanic acid, is 0.1%. The preferred amounts are between 01-20% although larger amounts may be used, even up to 6%, calculated as metal oxides, as disclosed in my co-pending application Serial No. 705,493, filed October 24, 1946, now abandoned.

Instead of using the above-mentioned insoluble compounds of elements of groups 2 to 5 of the periodic table, other sufiiciently water-insoluble organic acid salts forming white oxides on cal- .cination can likewise be employed. For instance,

insoluble salts of magnesium, zinc, aluminum,

4 beryllium, etc., and. myristic, palmitic, stearic, oleic, linoleic, linolenic and ricinoleic acids and their homologues can be used. Also, the insoluble salts of polybasic acids, such as sebacates, adipates, etc., can be employed.

The amount of compounds of the di-, tri-, tetra-, or pentavalent elements added to the metatitanic acid is from 0.1% to 6%, calculated as metallic oxides based on the T102 contents of the metatitanic acid, as in my co-pending application Serial No. 705,493, now abandoned.

The following examples will serve to illustrate the practice of this invention.

Example I To a thick aqueous slurry of metatitanic acid precipitate containing 350 grams TiOz is added 3 grams of Al(OH)3, which reacts with the H2SO4 contained in the metatitanic acid, forming watersoluble sulfates of aluminum. The mixture is agitated until the aluminum hydrate has reacted with the sulfuric acid of the metatitanic acid. A 15% solution of ammonia is then added until a pH of 10 is reached which results in precipitation of aluminum hydroxide. The slurry is filtered and washed until substantially free of ammonium sulfate. No peptization occurs.

Example II 'To an aqueous slurry of metatitanic acid precipitate containing 350 grams TiOz is added 1.84

Example II] To an aqueous slurry of metatitanic acid precipitate containing 350 grams TiOz is added 100 grams of a 4% potassium antimony tartrate solution. Enough of a 20% ammonia solution is then added, under thorough agitation, to bring the pH to 10 which results in precipitation of antimony hydroxide. The slurry is then filtered, and the precipitate is washed free of soluble salts. No peptization occurs.

Example IV An aqueous slurry of metatitanic acid precipitate containing 350 grams TiOz is neutralized with a 10% ammonia solution to 7-12 pH. 8.2 grams of basic zirconium carbonate is added as a water slurry and the whole mixture thoroughly agitated. The mixture is filtered and washed until free of salts, without encountering peptization.

The use of corresponding alkali metal compounds for neutralization before introduction of the compound of the specified class of metals is embodied in the claims of my co-pending application Ser. No. 190,890, filed October 18, 1950:

the use of corresponding alkali metal compounds for neutralization after introduction of the compound of the specified class of metals is embodied in the claims of my co-pending application Ser. No. 705,495, filed October 24, 1946; and the use of ammonium compounds for neutralization after introduction of the compound of the specified class of metals is embodied in the claims of my 5 co-pending application Ser. No. 705,494, filed October 24, 1946.

The present invention is not limited to the specific details set forth in the foregoing examples which should be construed as illustrative and not by way of limitation, and in view of the numerous modifications which may be eifected therein Without departing from the spirit and scope of this invention, it is desired that only such limitations be imposed as are indicated in the appended claims.

This application is a division of my application Serial No. 705,494, filed October 24, 1946.

I claim as my invention:

1. In a process of removing the S04 impurity from metatitanic acid produced by hydrolysis of an aqueous sulfuric acid solution of titanium sulfate, introducing into a slurry of said metatitanic acid a member of the alkaline group consisting of ammonium hydroxide, ammonium carbonate and ammonium basic carbonate to a 7-12 pH, then introducing into the slurry at least one member of the group consisting of the watersoluble salts, the oxides, hydroxides, carbonates and basic carbonates of Be, Cd, Al, La, Zr, Ce, Th, Cb, Sb and Ta in amount equal to 0.1 to 6 per cent calculated as metal oxide based on the TiOz content of the metatitanic acid, said member of the alkaline group being in sufiicient amount to neutralize all of the S04 content of the metatitanic acid and to react with any salt in the slurry resulting from the introduction of the member of the group consisting of the watersoluble salts, the oxides, hydroxides, carbonates and basic carbonates of said class of metals consisting of Be, Cd, Al, La, Zr, Ce, Th, Cb, Sb and Ta, filtering and then washing the residue until substantially free of soluble salts.

2. The process claimed in claim 1, wherein the metal of the class is aluminum.

3. The process claimed in claim '1, wherein the metal of the class is zirconium.

4. The process claimed in claim 1, wherein the metal of the class is antimony.

5. In a process of removing the S04 impurity from metatitanic acid produced by hydrolysis of an aqueous sulfuric acid solution of titanium sulfate, introducing into a slurry of said metatitanic acid a member of the alkaline group consisting of ammonium hydroxide, ammonium carbonate and ammonium basic carbonate to a 7-12 pH, then introducing into the slurry at least one member of the group consisting of the watersoluble salts of Be, Cd, Al, La, Zr, Ce, Th, Cb, Sb and Ta in amount equal to 0.1 to 6 per cent calculated as metal oxide based on the T102 content of the metatitanic acid, said member of the alkaline group being in sufficient amount to neutralize all of the S04 content-of the metatitanic acid and to react with any salt in the slurry resulting from the introduction of the member of the group consisting of the water-soluble salts of said class of metals consisting of Be, Cd, Al, La, Zr, Ce, Th, Cb, Sb and Ta, filtering and then washing the residue until substantially free of soluble salts.

6. In a process of removing the S04 impurity from metatitanic acid produced by hydrolysis of an aqueous sulfuric acid solution of titanium sulfate, introducing into a slurry of said metatitanic acid a member of the alkaline group consisting of ammonium hydroxide, ammonium carbonate and ammonium basic carbonate to a 7-12 pH, then introducing into the slurry at least one member of the group consisting of the oxides, hydroxides, carbonates and basic carbonates of Be, Cd, A1, La, Zr, Ce, Th, Cb, Sb and Ta n amount equal to 0.1 to 6 per cent calculated as metal oxide based on the TiOz content of the metatitanic acid, said member of the alkaline group being in sufiicient amount to neutralize all of the S04 content of the metatitanic acid, filtering and then washing the residue until substantially free of soluble salts.

MAX J. MAYER.

REFERENCES CITED UNITED STATES PATENTS Name Date Specht Mar. 11, 1930 Number 

1. IN A PROCESS OF REMOVING THE SO4 IMPURITY FROM METATITANIC ACID PRODUCED BY HYDROLYSIS OF AN AQUEOUS SULFURICACID SOLUTION OF TITANIUM SULFATE, INTRODUCING INTO A SLURRY OF SAID METATITANIC ACID A MEMBER OF THE ALKALINE GROUP CONSISTING OF AMMONIUM HYDROXIDE, AMMONIUM CARBONATE AND AMMONIUM BASIC CARBONATE TO A 7-12 PH, THEN INTRODUCING INTO THE SLURRY AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF THE WATERSOLUBLE SALTS, THE OXIDES, HYDROXIDES, CARBONATES AND BASIC CARBONATES OF BE, CD, AL, LA, ZR, CE, TH, CB, SB AND TA IN AMOUNT EQUAL TO 0.1 TO 6 PER CENT CALCULATED AS METAL OXIDE BASED ON THE TIO2 CONTENT OF THE METATITANIC ACID, SAID MEMBER OF THE ALKALINE GROUP BEING IN SUFFICIENT AMOUNT TO NEUTRALIZE ALL THE SO4 CONTENT OF THE METATITANIC ACID AND TO REACT WITH ANY SALT IN THE SLURRY RESULTING FROM THE INTRODUCTION OF THE MEMBER OF THE GROUP CONSISTING OF THE WATERSOLUBLE SALTS, THE OXIDES, HYDROXIDES, CARBONATES AND BASIC CARBONATES OF SAID CLASS OF METALS CONSISTING OF BE, CD, AL, LA, ZR, CE, TH, CB, SB AND TA, FILTERING AND THEN WASHING THE RESIDUE WITH SUBSTANTIALLY FREE OF SOLUBLE SALTS. 